Log Message:
Update ruby-rack-protection to 2.0.0.

No its own changes but here is related changes from Sinatra's changes.

 * Modernize Rack::Protection::ContentSecurityPolicy with CSP Level 2 and 3
   Directives #1202 by Glenn Rempe
 * Adds preload option to Rack:Protection:StrictTransport #1209 by Ed Robinson
 * rack-protection: Bundle StrictTransport, CookieTossing, and CSP #1267 by
   Mike Pastore